Rotary cutters are used extensively. One example of a rotary cutter is illustrated in U.S. Pat. No. 2,870,839 issued Jan. 27, 1959 to Duane. In that patent, a fibrous blanket is conveyed through a device in which a plurality of continuous longitudinal cuts or slits are made in the blanket using a slitter. Downstream of the slitter, a plurality of moving cutter blades, constituted in the form of rotary saw blades, cut the blanket into a number of rectangular, fluffed chunks suitable for blowing insulation.
In continuing U.S. patent applications Ser. Nos. 33,355 and 84,694, filed Apr. 26, 1979 and Oct. 15, 1979 respectively, of U.S. patent application, Ser. No. 834,616, filed Sept. 19, 1977 which is now abandoned, a process for making a diced insulation product is disclosed. In the machine generally represented in that application, blowing wool may be made by delaminating fibrous blankets using a rotary cutter or dicer. The dicer is provided with a plurality of flat blades which have been manufactured with a ground helical surface. The flat blades, affixed to a dicer head formed in the shape of a truncated pyramid, cooperate with a stationary bed knife to cut the blankets. The bed knife is mounted with its cutting edge adjacent to the rotary shaft and is designed to cooperate with the flat blades in such a manner that when a compressed strip of blanket material is fed between the bed knife and the helical cutting surfaces of the rotating flat blades a progressive cutting action known in the art as a "draw" cut is made on the fibrous blankets.
Draw cuts are well known and may be based upon the principle of disposing one or more cutter blades on a rotary shaft angularly with respect to the axis of rotation of the shaft. A stationary bed knife, with its cutting edge parallel to the axis of the rotary shaft, is mounted on an anvil adjacent to the rotary shaft, and is designed to cooperate with the rotary cutter blade in such a manner that when a strip of material is fed between the two cutting edges, the rotating blade comes into cooperative action with the stationary cutting edge progressively, starting at one end of the cutting edge of the bed knife and progressively executing a cut on the material as the blade continues its rotary movement.
Well-known grinders for grinding cutter blades are complex, difficult to operate and therefore expensive to operate. Consequently, the blades ground with these grinders are expensive. Furthermore, these grinders do not facilitate the formation of a helical cutting surface on a flat blade which may be readily mounted on a rotary cutter. With these grinding machines, unnecessary labor and undue time is needed to ensure that the blades are properly mounted on the arbor of the rotary cutter relative to the bed knife.